PROJECT SUMMARY. Attention-Deficit/Hyperactivity Disorder (ADHD) is one of the most common chronic conditions in childhood, with significantly higher rates and worse outcomes among socioeconomically disadvantaged children. Social adversities including unmet basic needs such as food insecurity, housing instability, and lack of quality child care emerge as potent risk factors for ADHD symptoms as early as the preschool years. The development of early intervention strategies for young children with both ADHD and socioeconomic disadvantage is critical for mitigating future impairment. New research demonstrates that a low intensity, family-centered screening and referral program (WE CARE) at well infant visits is feasible and can increase receipt of resources for unmet social needs (e.g. food, transportation, and parent education). Adapting this strategy to target preschoolers with emerging ADHD, who are typically first identified in primary care, could significantly impact clinical symptoms and disease trajectory during a critical developmental period. Therefore, the objective of this project is develop an early intervention strategy, adapted from the WE CARE program, targeting unmet social needs for low-income families of preschool-age children with emerging ADHD. The WE CARE intervention will be adapted on 3 key domains (for a new target population, content, and primary outcomes) through the pursuit of 3 interrelated studies. These are: 1) Examine the association between specific unmet social needs and ADHD symptoms in 7,565 nationally representative children age 3-5 from the National Survey for Children's Health (NSCH) and explore potential mediators of this association (including parental stress, activation, and unmet need for care) via structural equation modeling (SEM); 2) Identify parent-reported mechanisms by which unmet social needs exacerbate ADHD symptoms in preschool age children and how an intervention addressing these needs could improve clinical outcomes by conducting semi-structured interviews with 25 parents of preschoolers with ADHD symptoms; and 3) Conduct an adaptive, randomized pilot trial of a novel treatment model addressing unmet social needs with parents of 60 low-income children age 3-5 with ADHD symptoms. This research plan reflects Objective 3.2 of the NIMH Strategic Plan, to develop ways to tailor existing and new interventions to optimize outcomes, and addresses an urgent need to reduce socioeconomic disparities in pediatric mental health outcomes by targeting modifiable risk factors in vulnerable young children. These research aims will also serve as vehicles for pragmatic learning of the following training goals: 1) Learn advanced statistical modeling and measurement methods for social determinants research; 2) Gain expertise in intervention development to reduce mental health disparities; and 3) Obtain training in modern clinical trial design for the study of psychosocial and health services interventions. This mentored K23 award will facilitate Dr. Spencer's long-term goal of becoming an independent investigator developing novel interventions to reduce socioeconomic inequities in pediatric psychiatric outcomes.